Digital rights management (DRM) is an extremely important consideration in connection with the ever-growing distribution of digital content, such as digital audio, digital video, digital text, digital data, digital multimedia, etc. Typically, the owner of rights in the digital content desires to distribute such content to a user or recipient in exchange for a license fee or some other consideration. The owner may further desire to restrict what the user can do with such distributed digital content. For example, the owner may desire to restrict the user from copying and re-distributing such content to a second user, at least in a manner that denies the content owner a license fee from such second user.
In certain situations, a digital-content recipient may desire to communicate the content from one electronic device to another. For example, a recipient may desire to receive digital content at a server and pass the content along to a client device that, in turn, is operable to render the content to a presentation device, such as a television, stereo system or the like. It is often further desirable, for DRM purposes, to ensure that the client device outputs the content to the presentation device in accordance with a set of rules, such as a protection policy, associated with the content. Such protection policies may be in accordance with, for example, the CGMS-A and Macrovision DRM standards, and the like. To this end, the server may transmit the protection policy along with the content to the client device, thereby allowing the client device to process and implement the protection policy in conjunction with rendering the content. Moreover, the server may encrypt the content with a key and provide the key to the client device for content decryption subject to the ability of the client device to implement the protection policy.
Among the different types of restricted-use media that can be provided by a server to a client device, television and other long-playing data streams are unusual in that they may not be associated with a single fixed protection policy. During the course of a restricted-use television-streaming session, the protection policy can change as certain restrictions are applied or removed. A change in policy may be necessitated by, for example, a transition from one program to another or a transition from one channel to another. A problem associated with such changes in policy is the need to process the new policy and an associated key to accommodate the new policy, thereby causing the viewer of the television stream to encounter unwanted delays in viewing content subject to the new policy.